JP2009151097A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus increasing a widthwise movement distance of a belt member with respect to an inclination angle of a steering rotational body without relying on the winding angle of the belt member or the diameter of the steering rotational body. <P>SOLUTION: A steering mechanism 30 moves an intermediary transfer belt 31 in its width direction by moving an inclination angle of steering rollers 77 and 78 with respect to a rotational direction of the intermediary transfer belt 31. The steering rollers 77 and 78 change the inclination angle while maintaining a rectangle defined by the steering rollers 77 and 78 and bearing arms 75, 74, and 79 to ensure a thrust movement distance in positions from start of winding of the steering roller 77 and end of winding of the other steering roller 78. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an image forming apparatus that dynamically positions a rotating belt member in the width direction by changing the tilt angle of a steering rotator, and more particularly to a structure that increases the amount of movement of the belt member in the width direction with respect to the amount of change in tilt angle. .

  An image forming apparatus for transferring a toner image from an image carrier to a recording material carried on a recording material conveyance belt, and a toner image primarily transferred from the image carrier to an intermediate transfer belt is secondarily transferred from the intermediate transfer belt to the recording material. An image forming apparatus has been put into practical use. An image forming apparatus in which a toner image transferred to a recording material is nipped and conveyed by a fixing belt to be heat-fixed on the recording material has been put into practical use.

  For such a belt member, a steering mechanism that dynamically positions the rotating belt member in the width direction by changing the tilt angle of the steering rotating body has been put into practical use.

  Patent Document 1 discloses an image forming apparatus that positions a rotating intermediate transfer belt in a width direction using a steering mechanism. Here, two steering rotators are arranged and interlocked with a distance in the rotation direction of the belt member, but the inclination angles of the two steering rotators with respect to the rotation direction of the belt member are controlled in different directions. Is done.

  Patent Document 2 discloses a steering mechanism that cancels tension fluctuations caused by tilting of a steering rotator by controlling the amount of inclination of the tension rotator disposed at a position separated in the rotation direction of the belt member.

JP 2000-233843 A JP 2001-147601 A

  When the steering rotator is tilted by the angle θ with respect to the rotation direction of the belt member, the amount of movement in the width direction is the length obtained by multiplying the winding length of the belt member by cos θ. The amount of movement increases.

  In order to increase the winding length of the belt member with respect to the steering rotating body, the winding angle of the belt member is increased or the diameter of the steering rotating body is increased.

  However, when the wrapping angle of the belt member is increased, the steering rotator protrudes greatly to the outside and the fit into the image forming apparatus is deteriorated.

  Further, when the diameter of the steering rotator is increased, the tilt angle is limited by interference with other rotators supporting the belt member, and the fit into the image forming apparatus becomes worse.

  Therefore, in any case, it is not easy to incorporate the belt into the drive mechanism of the belt member in which a rotation path is determined and a large number of devices are arranged around.

  An object of the present invention is to provide an image forming apparatus in which the amount of movement of the belt member in the width direction with respect to the tilt angle of the steering rotating body is increased without depending on the winding angle of the belt member and the diameter of the steering rotating body.

  An image forming apparatus of the present invention includes a belt member that is supported by a plurality of rotating bodies and rotates, and a steering mechanism that moves and positions the rotating belt members in the axial direction of the plurality of rotating bodies. is there. The steering mechanism rotates in contact with the inner surface of the rotating belt member, and a first steering rotating body in which an inclination angle with respect to the rotation direction of the belt member is changed, and the first steering rotating body The belt member is stretched between and rotated, and the second steering rotating body whose inclination angle with respect to the rotation direction of the belt member is changed, and the first steering rotating body and the second steering rotating body are interlocked. And an interlocking mechanism for changing the tilt angle in the same direction.

  In the image forming apparatus of the present invention, the length from the start of winding around the upstream steering rotator to the end of winding around the downstream steering rotator functions as the winding length of one steering rotator. The portion of the belt member that is not in contact with the steering rotator positioned between the upstream steering rotator and the downstream steering rotator also functions as the winding length of one steering rotator.

  Therefore, the amount of movement of the belt member in the width direction with respect to the tilt angle of the steering rotating body can be increased without depending on the winding angle of the belt member and the diameter of the steering rotating body.

  Hereinafter, some embodiments of the present invention will be described in detail with reference to the drawings. As long as the position of the belt member in the width direction is dynamically controlled, the image forming apparatus of the present invention is realized in another embodiment in which a part or all of the configuration of each embodiment is replaced with the alternative configuration. Is possible. Accordingly, not only the intermediate transfer belt but also a recording material conveying belt, a photosensitive belt, a transfer belt, a secondary transfer belt, and a fixing belt can be used.

  Not only a tandem type full-color image forming apparatus but also an image forming apparatus in which a plurality of developing devices are attached to one image carrier, an image forming apparatus having three or less image carriers attached to an intermediate transfer member or a recording material carrier. Can be implemented.

  In the present embodiment, only main parts related to toner image formation / transfer will be described. However, the present invention includes a printer, various printing machines, a copier, a fax machine, a composite machine, in addition to necessary equipment, equipment, and a housing structure. It can be implemented in various applications such as a machine.

  In addition, about the general matter of the image forming apparatus shown by patent document 1, 2, illustration is abbreviate | omitted and the overlapping description is abbreviate | omitted.

<First Embodiment>
FIG. 1 is an explanatory diagram of a configuration of the image forming apparatus according to the first embodiment.

  As shown in FIG. 1, the image forming apparatus 100 according to the first embodiment is a tandem intermediate transfer type full-color copying machine in which four image forming units SA, SB, SC, and SD are arranged in a linear section of an intermediate transfer belt 31. It is.

  In the image forming unit SD, a yellow toner image is formed on the photosensitive drum 11 d and is primarily transferred to the intermediate transfer belt 31. In the image forming unit SC, a magenta toner image is formed on the photosensitive drum 11 c and is primarily transferred to the yellow toner image on the intermediate transfer belt 31. In the image forming units SB and SA, a cyan toner image and a black toner image are formed on the photosensitive drums 11b and 11a, respectively, and are similarly primarily transferred to the intermediate transfer belt 31.

  The four-color toner images primarily transferred to the intermediate transfer belt 31 are conveyed to the secondary transfer portion T2, and are collectively secondary transferred to the recording material P fed to the secondary transfer portion T2. The recording material P on which the toner image is secondarily transferred is stacked on the discharge tray 48 after the toner image is fixed by the fixing device 40.

  The separating device 23 separates the recording material P drawn from the sheet feeding cassette 21 by the pickup roller 22 one by one and sends it to the registration roller 25.

  The registration roller 25 sandwiches and conveys the recording material P in synchronization with the toner image on the intermediate transfer belt 31 and feeds it to the secondary transfer portion T2.

  The intermediate transfer belt 31 is supported by the drive roller 32, the steering rollers 77 and 78, the backup roller 34, and the support rollers 62 and 63 so as to be movable in the width direction. The intermediate transfer belt 31 is driven by a motor M1 that rotates a driving roller 32, and rotates in a direction indicated by an arrow R2 at a predetermined process speed.

  The intermediate transfer belt 31 is formed endlessly with a 100 μm thick polyimide resin (PI) containing carbon black and imparting resistance. The intermediate transfer belt 31 may be formed of PVdF [polyvinylidene fluoride] or the like.

  The image forming units SA, SB, SC, and SD are configured in the same manner except that the toner colors used in the attached developing devices 14a, 14b, 14c, and 14d are different from black, cyan, magenta, and yellow. Hereinafter, the black image forming unit SA will be described, and the other image forming units SB, SC, and SD will be described by replacing “a” at the end of the reference numerals with “b”, “c”, and “d”.

  In the image forming unit SA, a primary charging device 12a, an exposure device 13a, a developing device 14a, a primary transfer roller 35a, and a cleaning device 15a are arranged around the photosensitive drum 11a.

  The photosensitive drum 11a has a negatively charged photosensitive layer formed on the outer peripheral surface of an aluminum cylinder. The photosensitive drum 11a is rotatably supported at both ends, and is rotated in the direction of the arrow R1 by transmitting a driving force from a driving motor (not shown) to one end.

  The primary charging device 12a charges the surface of the photosensitive drum 11a to a uniform negative potential.

  The exposure device 13a scans the scanning line image data obtained by developing the black separated color image with a polyhedral mirror, and writes an electrostatic image of the image on the surface of the photosensitive drum 11a.

  The developing device 14a supplies the negatively charged toner to the photosensitive drum 11a, adheres it to the exposed portion of the electrostatic image, and reversely develops the electrostatic image.

  The primary transfer roller 35 a is pressed against the photosensitive drum 11 a via the intermediate transfer belt 31 to form a primary transfer portion T 1 between the photosensitive drum 11 a and the intermediate transfer belt 31.

  In the process where the toner image carried on the photosensitive drum 11a passes through the primary transfer portion T1, a positive DC voltage is applied to the primary transfer roller 35a, whereby the toner image is primarily transferred to the intermediate transfer belt 31.

The primary transfer roller 35a is formed to have an outer diameter of 16 mm by covering a surface layer 35h of urethane sponge, in which an ion conductive conductive agent is dispersed and the resistance value is adjusted to 5 × 10 ⁷ Ω, on a core metal having a diameter of 8 mm.

  The cleaning device 15a removes transfer residual toner remaining on the surface of the photosensitive drum 11a after passing through the primary transfer portion T1.

  The secondary transfer roller 36 is a rubber roller imparted with electrical conductivity. The secondary transfer roller 36 is pressed against the backup roller 34 via the intermediate transfer belt 31, and a secondary transfer portion is interposed between the intermediate transfer belt 31 and the secondary transfer roller 36. T2 is formed.

  In the process in which the recording material P is nipped and conveyed over the toner image on the intermediate transfer belt 31, a positive voltage is applied to the secondary transfer roller 36 from a power source (not shown), and the intermediate transfer belt 31. The toner image carried on the toner image is secondarily transferred to the recording material P.

  The backup roller 34 is connected to the ground potential, bends the circulation path of the intermediate transfer belt 31 on the downstream side of the secondary transfer portion T2, and separates the recording material P attached to the intermediate transfer belt 31 by curvature.

  The fixing device 40 presses a pressure roller 42 against a fixing roller 41 having a heat source 43 to form a fixing nip, and sandwiches and conveys the recording material P onto which the toner image has been secondarily transferred while being heated and pressed. A toner image is fixed on the surface of the toner.

  The cleaning device 47 removes transfer residual toner remaining on the intermediate transfer belt 31 after passing through the secondary transfer portion T2.

  In the intermediate transfer belt 31, due to the alignment error of the plurality of rotating bodies that support the inner peripheral surface, a movement in the belt width direction, that is, a so-called belt shift occurs along with the rotation.

  If the belt shift is left unattended, the intermediate transfer belt 31 moves out of the support range of the rotating body and causes damage or dropout of the intermediate transfer belt 31. Therefore, the image forming apparatus 100 performs steering control to correct the belt shift. ing.

  The steering control is a roller steering type belt deviation regulating method in which the inclination of the steering rollers 77 and 78 that support the inner peripheral surface of the intermediate transfer belt 31 is changed to correct the belt deviation.

  In the roller steering system, the steering amount of the steering rollers 77 and 78 is appropriately controlled in a timely manner, so that the shift of the intermediate transfer belt 31 can be kept within the support range of the rotating body. Then, belt shift regulation can be performed without applying stress to the intermediate transfer belt 31.

  For this reason, in a highly productive image forming apparatus that requires a certain level of durability, such a roller steering type steering mechanism is often used.

<Steering control>
FIG. 2 is an explanatory diagram of the steering control system of the intermediate transfer belt.

  As shown in FIG. 2 with reference to FIG. 1, the control unit 50 operates the steering mechanism 30 based on the outputs of the belt edge sensors 54 and 55 to position the rotational position of the intermediate transfer belt 31 in the width direction. .

  The belt edge sensors 55 and 56 input an analog voltage corresponding to the rotation angle of the flag in contact with the belt edge to the control unit 50.

  The control unit 50 includes a control board for controlling the operation of a mechanism in each unit of the image forming apparatus 100, a motor drive board (not shown), and the like.

  When the belt edge sensor 54 detects the approach of the belt edge, the control unit 50 operates the steering mechanism 30 to move the intermediate transfer belt 31 to the back side. At this time, the controller 50 operates the pulse motor 83 to lower the rotation shaft ends on the front side of the steering rollers 77 and 78. As a result, the end of winding of the intermediate transfer belt 31 around the steering roller 77 is shifted to the back side rather than the start of winding of the intermediate transfer belt 31 around the steering roller 77, so that the rotating intermediate transfer belt gradually moves toward the back side.

  When the belt edge sensor 55 detects the approach of the belt edge, the control unit 50 operates the steering mechanism 30 to move the intermediate transfer belt 31 to the front side. At this time, the control unit 50 operates the pulse motor 83 to raise the rotation shaft end on the front side of the steering rollers 77 and 78. As a result, the winding end of the intermediate transfer belt 31 around the steering roller 77 is shifted to the front side rather than the winding start of the intermediate transfer belt 31 around the steering roller 77, so that the rotating intermediate transfer belt gradually moves toward the back side.

  The steering mechanism 30 rotates the steering rollers 77 and 78 in contact with the inner surface of the intermediate transfer belt 31 in the section of the intermediate transfer belt 31 divided by the support rollers 62 and 63. The steering mechanism 30 positions the rotating intermediate transfer belt 31 in the width direction by changing the tilt angles of the steering rollers 77 and 78 with respect to the rotation direction of the intermediate transfer belt 31 in the same direction.

  The support rollers 62 and 63 are disposed with the steering rollers 77 and 78 sandwiched in the rotation direction of the intermediate transfer belt 31, and the inclination angle of the steering rollers 77 and 78 is within a range where the intermediate transfer belt 31 is not separated from the support rollers 62 and 63. It is controlled by.

  The support roller 62 blocks the inclination of the intermediate transfer belt 31 due to the inclination of the steering roller 77 and forms a fixed transfer plane between the support roller 62 and the drive roller 32. The support roller 63 blocks the inclination of the intermediate transfer belt 31 due to the inclination of the steering roller 78 and keeps the surface of the intermediate transfer belt 31 on the secondary transfer portion T2 side constant.

<Steering mechanism>
3 is a perspective view of the steering mechanism, FIG. 4 is a front view of the steering mechanism, FIG. 5 is a rear view of the steering mechanism, FIG. 6 is an explanatory view of the operation of the steering mechanism, and FIG. is there.

  As shown in FIG. 3, the steering mechanism 30 moves the intermediate transfer belt 31 in the width direction by changing the inclination angle of the steering rollers 77 and 78 with respect to the rotation direction of the intermediate transfer belt 31.

  The steering roller 77 is rotatable with the front-side rotation shaft end held by the bearing arm 74 and the back-side rotation shaft end held by the bearing arm 75. The bearing arm 74 is held by the holding arm 72 so as to be slidable in the direction along the holding arm 72.

  The steering roller 78 rotates with the intermediate transfer belt 31 stretched between the steering roller 77. The steering roller 78 has a rotating shaft end on the front side held by a bearing arm 79 fixed to the bearing arm 74, and a rotating shaft end on the back side held by a bearing arm 75 and is rotatable. The bearing arm 75 is held by the holding arm 73 so as to be slidable in the direction along the holding arm 72.

  The bearing arms 74 and 75 are rotatably held with respect to the holding arms 72 and 73 in a plane perpendicular to the direction along the holding arms 72 and 73, respectively. Accordingly, the steering rollers 77 and 78 change the inclination angle while maintaining the rectangular shape constituted by the steering rollers 77 and 78 and the bearing arms 75, 74 and 79.

  Therefore, the interlocking mechanism (72, 74, 79, 73, 75) supports the first steering rotating body (77) and the second steering rotating body (78) rotatably at the rotating end, and rotates. It has a rotation member (72, 74, 79) for moving the rotation end.

  As shown in FIG. 4, the holding arm 72 on the front side is rotatably attached to a rotating shaft 76 fixed to the unit frame 64, and is urged clockwise by a spring (not shown) to cam the lower surface. 65 abuts. Therefore, the rotation position of the holding arm 72 around the rotation shaft 76 is positioned at the abutting height of the holding arm 72 with respect to the cam surface of the cam 65.

  An urging spring 70 is disposed between the bearing arm 74 and the holding arm 72, and urges the bearing arm 74 outward along the holding arm 72. As a result, the bearing arms 74 and 79 are pushed outward to bring the steering rollers 77 and 78 into pressure contact with the inner side surface of the intermediate transfer belt 31, and necessary tension is applied to the front side of the intermediate transfer belt 31.

  As shown in FIG. 5, the holding arm 73 on the back side is fixedly supported by the unit frame 64 and does not rotate.

  An urging spring 71 is disposed between the bearing arm 75 and the holding arm 73 to urge the bearing arm 75 in the outward direction along the holding arm 73. As a result, the bearing arm 75 is pushed outward to bring the steering rollers 77 and 78 into pressure contact with the inner surface of the intermediate transfer belt 31, thereby applying the necessary tension to the back side of the intermediate transfer belt 31.

  As shown in FIG. 4, the bearing arm 79 is fixed to the bearing arm 74 via an alignment adjusting mechanism 79a. Therefore, by loosening the alignment adjustment mechanism 79a, the rotation shaft end on one side of the steering roller 78 in the direction along the holding arm 72 (the amount of protrusion toward the belt member) and the direction toward the steering roller 77 (the shaft end distance). Can be fixed by moving. The alignment adjusting mechanism 79a is adjusted so that the relative alignment of the steering rollers 77 and 78 substantially matches.

  Further, a rubber layer is formed on the roller surfaces of the steering rollers 77 and 78 so that a good grip for the belt can be maintained.

  As shown in FIG. 6, by operating the pulse motor 83 to rotate the cam 65, the holding arm 72 is rotated to raise and lower the rotation shaft end on the front side of the steering rollers 77 and 78. At this time, the rotating shaft end on the back side of the steering rollers 77 and 78 does not move up and down.

  As shown in FIG. 7, the steering rollers 77 and 78 are fixed in relative positional relationship (without being displaced in the axial direction), and have an inclination angle with respect to the rotation direction of the intermediate transfer belt (31: FIG. 3). Change.

  As a result, a relative position difference is generated in front of the holding arms 72 and 73, and the steering rollers 77 and 78 are steered. Since the steering rollers 77 and 78 are well adjusted in relative alignment with each other, the restraint conveyance direction of the intermediate transfer belt 31 is the same. Further, since a good belt grip is maintained by the surface-treated rubber layer, belt restraint conveyance in the steering direction including the stretched portion between the steering rollers 77 and 78 can be performed.

  Thus, an inclination angle θ is given over a distance dm from the start of winding around the steering roller 77 to the end of winding around the steering roller 78. Then, a thrust movement amount d of the intermediate transfer belt 31 at the belt winding portion of the steering rollers 77 and 78 is given. As a result, it is possible to give the intermediate transfer belt 31 a large shift speed with high sensitivity according to the rotation angle of the cam 65.

  In the first embodiment, the intermediate transfer belt 31 is used as a belt member. However, the present invention can also be suitably applied to other belt conveying means provided with a steering mechanism such as a fixing device.

<Comparative Example 1>
8 is a front view of the steering mechanism of Comparative Example 1, FIG. 9 is an explanatory diagram of the operation of the steering mechanism of Comparative Example 1, and FIG. 10 is an explanatory diagram of the steering performance of the steering roller. FIG. 11 is an explanatory diagram of the belt movement amount.

  Comparative Example 1 is a conventional example in which the steering rollers 78 and 79 in the steering mechanism of FIG. 3 are replaced with one steering roller 78A having a large diameter.

  As shown in FIG. 8, in the steering mechanism 30A of Comparative Example 1, the intermediate transfer belt 31 is steered by a single large-diameter steering roller 77A disposed between the support rollers 62 and 63.

  Since the holding arm 72A on the front side is rotatably attached to the rotating shaft 76, and the lower surface is in contact with the cam 65, the rotating position of the holding arm 72A is the height at which the holding arm 72A hits the cam 65. Now it is positioned.

  The bearing arm 74A is slidably held with respect to the holding arm 72A, and an urging spring 70A is disposed between the bearing arm 74A and the holding arm 72A to urge the bearing arm 74A outward. . Thereby, necessary tension is applied to the front side of the intermediate transfer belt 31.

  On the rear side of the steering mechanism 30A, the rotating shaft end of the steering roller 77A is held so as to be slidable in the horizontal direction, and is urged outward by an urging spring (71A: not shown).

  As shown in FIG. 9, the pulse motor 83 is actuated to rotate the cam shaft 82 by a predetermined angle, the cam 65 acts to rotate the front holding arm 72A, and the front rotating shaft of the steering roller 77A. Raise the edge.

  As shown in FIG. 10, at this time, even if the rotation amount of the cam shaft 82 is given as in the case of FIG. 6, the belt thrust movement amount d is significantly reduced.

  As shown in FIG. 11B, the steering function of the steering roller 77 </ b> A changes the inclination angle θ of the steering roller 77 </ b> A with respect to the rotation direction of the intermediate transfer belt 31.

  As shown in FIG. 11A, the intermediate transfer belt 31 is displaced in the longitudinal direction of the roller (thrust movement amount d) between the winding start point 103 and the winding end point 104 of the intermediate transfer belt 31 with respect to the tearing roller 77A. Is moved in the width direction.

  As shown in FIG. 11B, the intermediate transfer belt 31 continuously moves in the axial direction of the steering roller 77A by obtaining this thrust movement amount d once per round. By controlling the thrust movement amount d by the movement amount ε (hereinafter referred to as the steering amount ε) of the end portion of the steering roller 77A, the steering control of the intermediate transfer belt 31 can be performed.

As shown in FIG. 11A, the distance between the winding start point 103 and the winding end point 104 is dm, the angle between the distance dm direction and the steering direction is φs, and the length of the steering roller 77A is ks. At this time, the following relationship is established between the belt steering amount ε and the thrust movement amount d of the intermediate transfer belt 31 by the steering roller 77A.
d = ε * dm / ks * cos (φs) (1)

  Therefore, in order to increase the thrust movement amount d, it is necessary to increase the distance dm by increasing the diameter of the steering roller 77A or increasing the winding angle of the intermediate transfer belt 31.

  However, as shown in FIG. 1, the steering mechanism 30 may not be able to arrange the steering roller 77A having a sufficient diameter due to a cross-sectional restriction, or may not have a sufficient winding angle with respect to the steering roller 77A.

  In such a case, the value of the distance dm becomes small, the thrust movement amount d for steering control becomes insufficient, and an overshoot of the intermediate transfer belt 31 may occur.

  Further, when the thrust movement amount d is increased when the distance dm is small, the steering amount ε of the steering roller 77A is increased. In this case, the image may be greatly distorted or the steering roller 77A may not be able to restrain the intermediate transfer belt 31 due to the tension of the intermediate transfer belt 31, resulting in a problem in steering control.

<Comparative example 2>
12 is a front view of the steering mechanism of Comparative Example 2, FIG. 13 is an explanatory view of the steering performance of the steering roller, FIG. 14 is an explanatory view of the out-of-plane deformation of the intermediate transfer belt, and FIG. 15 is an in-plane deformation of the intermediate transfer belt. It is explanatory drawing.

  In Comparative Example 2, the support roller 100 whose inclination angle is not interlocked with the steering rollers 77 and 78 is disposed between the steering rollers 77 and 78 described in the first embodiment.

  As shown in FIG. 12, when the steering rollers 77 and 78 that are not adjacent to each other are steered, as shown in FIG. 13, the obtained belt thrust movement amount d is significantly smaller than that in the first embodiment shown in FIG.

  This is because the support roller 100 that does not interlock with the alignment change is inserted between the steering rollers 77 and 78, and as a result, as shown in FIG. Since the intermediate transfer belt 31 is lifted at one end of the support roller 100, the vectors in the belt conveyance direction of the steering rollers 77 and 78 are not stored.

  On the other hand, the steering mechanism 30 according to the first embodiment can realize belt conveyance capable of good belt conveyance with a large shift control range with an easy configuration in a small space.

  The reason will be described below.

  As shown in FIG. 7, when the intermediate transfer belt 31 is steering-controlled in conjunction with the steering rollers 77 and 78, the distance from the belt winding start of the steering roller 77 to the belt winding end of the steering roller 78 is expressed by the equation (1). It can be regarded as the distance dm. However, it is necessary that the steering rollers 77 and 78 have sufficient belt binding force and the steering rollers 77 and 78 have good relative alignment.

  Many belt members such as an intermediate transfer belt, a recording material conveyance belt, and a fixing belt used in an image forming apparatus have a base layer such as PI (polyimide) that cannot be stretched greatly.

  Such a belt member can be easily deformed out-of-plane as shown in FIG. 14, but hardly undergoes in-plane deformation as shown in FIG.

  For this reason, the intermediate transfer belt 31 fed out from the end of winding of the steering roller 77 is restrained to some extent in this feeding direction. If it is wound around the steering roller 78 facing the same conveyance direction while this restriction is effective, the portion between the rollers can be restricted along the conveyance vector of the steering roller 77, 78 by the cooperation of the steering rollers 77, 78. As a result, a large distance dm from the start of winding of the steering roller 77 to the end of winding of the steering roller 78 can be obtained in a small space.

  Therefore, aligning the conveyance vectors of the steering rollers 77 and 78 is a very important adjustment. In the first embodiment, an alignment adjustment mechanism 79a is provided, and the distance between the rotation shaft end of the first steering rotation body and the rotation shaft end of the second steering rotation body, and the rotation shaft of the rotation member and the second steering rotation. It can be fixed by adjusting the distance from the rotation axis end of the body. For this reason, when assembling using a jig, the conveyance vectors of the steering rollers 77 and 78 can be precisely and easily aligned.

  It is also very important that the steering rollers 77 and 78 have a sufficient belt restraining force. In the first embodiment, the steering rollers 77 and 78 are subjected to a surface treatment of the rubber layer so that the friction coefficient is higher than that of the other plurality of rotating bodies.

It is explanatory drawing of a structure of the image forming apparatus of 1st Embodiment. 3 is an explanatory diagram of a steering control system of an intermediate transfer belt. FIG. It is a perspective view of a steering mechanism. It is a front view of a steering mechanism. It is a rear view of a steering mechanism. It is explanatory drawing of operation | movement of a steering mechanism. It is explanatory drawing of the steering performance of a steering roller. 6 is a front view of a steering mechanism of Comparative Example 1. FIG. 6 is an explanatory diagram of the operation of the steering mechanism of Comparative Example 1. FIG. It is explanatory drawing of the steering performance of a steering roller. It is explanatory drawing of the amount of belt movement. 10 is a front view of a steering mechanism of Comparative Example 2. FIG. It is explanatory drawing of the steering performance of a steering roller. FIG. 6 is an explanatory diagram of out-of-plane deformation of an intermediate transfer belt. FIG. 6 is an explanatory diagram of in-plane deformation of an intermediate transfer belt.

Explanation of symbols

30 Steering mechanism 31 Belt member (intermediate transfer belt)
32, 34, 77, 78 Rotating body (drive roller, backup roller, tension roller)
50 Control units 72, 73 Rotating members (holding arms)
74, 75, 79, 72, 73 Interlocking mechanism (bearing arm, holding arm)
77 First steering rotating body (steering roller)
78 Second steering rotating body (steering roller)
79a Adjustment mechanism (alignment adjustment mechanism)
83 Pulse motor 100 Image forming apparatus SA, SB, SC, SD Image forming unit

Claims (6)

A belt member that is supported by a plurality of rotating bodies and rotates;
A steering mechanism that moves and positions the rotating belt member in the axial direction of the plurality of rotating bodies, and an image forming apparatus comprising:
The steering mechanism is
A first steering rotator that rotates in contact with an inner surface of the rotating belt member and changes an inclination angle with respect to a rotation direction of the belt member;
A second steering rotating body in which the belt member is stretched and rotated with the first steering rotating body, and an inclination angle with respect to a rotation direction of the belt member is changed;
An image forming apparatus comprising: an interlocking mechanism that interlocks the first steering rotating body and the second steering rotating body to change the tilt angle in the same direction.   The image forming apparatus according to claim 1, wherein the interlocking mechanism fixes a positional relationship between the first steering rotator and the second steering rotator.   The image forming apparatus according to claim 2, wherein the interlocking mechanism includes an adjustment mechanism that can be fixed by adjusting a shaft end distance between one side of the first steering rotator and the second steering rotator.   The adjustment mechanism can be fixed by adjusting a difference in a protruding amount of the first steering rotating body and the second steering rotating body toward the belt member at the shaft end on one side. 3. The image forming apparatus according to 3.   5. The first steering rotator and the second steering rotator have a surface treatment such that a friction coefficient is higher than that of the other plurality of rotators. 6. Image forming apparatus.   The interlocking mechanism rotatably supports the first steering rotating body and the second steering rotating body on the rotating end of a rotating member that rotates to move the rotating end. The image forming apparatus according to claim 1.

Images